Modeling of the coefficient of thermal expansion of 3D-printed composites

This study examines the coefficient of thermal expansion (CTE) in 3D-printed composites reinforced with short fibers. A novel analytical approach is introduced rooted in extracting fibers from micro computer tomography images to account for their aspect ratio distribution. Utilizing a novel method based on the inertia tensor of ellipsoids. This method enables the conversion of fibers into equivalent ellipsoids, obtaining their respective aspect ratios. Subsequently, these ellipsoids are incorporated into three effective field methods - the Non-Interaction, the Mori-Tanaka, and the Maxwell methods - to assess the composite's CTE. This methodology is applied to recycled poly(ethylene terephthalate) reinforced with recycled short carbon fibers (rcPET) that is used in additive manufacturing for composite parts. The analytical results demonstrate good agreement with experimental data sourced from the open literature.